The present invention relates to a machine for winding and inserting coils of the stator of a 3-phase multipolar motor and, more particularly, to a coil winding and insertion machine in which the coils are directly wound around tooling blades of an inserter and then inserted into the slots of the stator core.
A coil winding and inserting machine of the aforementioned type is disclosed, for example, in U.S. Pat. No. 4,299,023, wherein coils are directly wound around the tooling blades of the inserter, with the thus wound coils being directly inserted into the slots of the stator core.
This coil winding and inserting machine is suitable for winding and inserting the stator coil of variable speed motors, i.e. motors having at least two different speeds, such as single-phase 4-pole motors.
More specifically, this known machine has three winding means and a coil winding head. As the coil winding head is located in sequence beneath three winding means, the main coils for high-speed operation, main coils for low-speed operation and an auxiliary coils for determining the rotation direction at the time of starting of the motor are formed successively by the first winding means, second winding means and the third winding means, respectively, and the thus formed coils are inserted into the slots in the stator core at the insertion station.
This machine, however, cannot apply to the winding and insertion of the stator coils of 3-phase multipolar motor because, in such a use, this machine cannot make a continuous winding of a each phase without discontinuity of crossover wire between the poles.
Namely, in the stator coil of a 3-phase bipolar motor, three phases u, v and w are arranged at 120.degree. phase differential, with each phase having two poles arranged at 180.degree. interval. The coils of the first pole of all phases are required to have an equal circumferential length and the same applies also to the coils of the second pole.
For effecting the coil winding with this machine without cutting the crossover wire between poles, it is necessary to take the following procedure that the winding is at first made by the first winding means to make the two poles of the u phase and then by the second winding means to make the two poles of the v phase followed by the winding of the two poles of the w phase by the third winding means. Consequently, coils of the u phase, v phase and the w phase are wound at the lowermost stage, intermediate stage and the uppermost stage in the coil winding head, respectively. As these coils are inserted into the stator core, coils are arranged in three stages in the order of u, v and w from the center to the outer side of the stator core. This means that lengths of the end turns of respective phases u, v and w on the end surface of the stator core are varied such that the length of end turns of u phase is smaller than that of the v phase which in turn is smaller than that of the w phase. Consequently, different phases have different circumferential lengths of coils and, hence, different electric resistances in the coils. Therefore, when the same voltage is applied to all phases, the driving torque generated in the stator coils fluctuates to cause an unsmooth rotation of the rotor of the motor, as well as vibration in the motor.
To avoid this problem, conventionally, the winding and insertion of the stator core of the 3-phase multipolar motor have been made by such a process including the steps of winding coils for each pole by a conventional winding machine, mounting the coils on an insert tooling in a predetermined sequence, inserting these coils to a stator core, and connecting the cross-over wires between poles of each phase.
This process is quite inefficient because it requires various troublesome works such as transfer of the coils from the coil winding means to the inserter tooling, connection of crossover wires between poles and so forth. In addition, the wires of the coils tend to become disoriented during the transfer to the inserter tooling, resulting in a deterioration of the quality of the coil after the insertion due to, for example, a cutting of the coil wire, a degradation of the insulation characteristics caused by damage on the wire, a projection of the coil out of the wedge, and so forth.